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Biomedical subjects

H T Nguyen

Publications and source records attributed to H T Nguyen.

At least 145 records · Page 8Linked to original sources
PubMed1994

Subacute sclerosing panencephalitis in an infant: diagnostic role of viral genome analysis.

Subacute sclerosing panencephalitis (SSPE) is related to "defective" measles virus or vaccination, though an association with parainfluenza viruses has been reported. SSPE is characterized by a slow, erratic course and elevated cerebrospinal fluid measles titers. An immunocompetent, vaccinated infant, with onset of symptoms in parainfluenza virus season and a catastrophic course is described. Cerebrospinal fluid titers were negative, but postmortem brain had typical SSPE lesions. Patient brain-derived RNA, subjected to reverse transcription followed by polymerase chain reaction yielded polymerase chain reaction products with measles virus but not parainfluenza virus genes. The sequenced fragment revealed multiple mutations, typical for SSPE. SSPE can thus present in infants, with short latency and no cerebrospinal fluid antibodies. Viral genomic analysis may be diagnostic, permitting early therapy.

Antigens, Viral↗
PubMed1994

Intracranial abnormalities and neurodevelopmental status after venovenous extracorporeal membrane oxygenation.

Computed tomography scans of the head and early neurodevelopmental assessment (Bayley Scales of Infant development) were recorded for 24 surviving infants who received venovenous extracorporeal membrane oxygenation and were compared with those of infants treated with venoarterial bypass matched by diagnosis and oxygenation index before extracorporeal membrane oxygenation. A comparable neuroradiographic and early neurodevelopmental outcome was documented for survivors of venoarterial and venovenous extracorporeal membrane oxygenation.

Brain↗
PubMed1994

Bacterial endotoxin increases type II phospholipase A2 immunoreactive content and phospholipase A2 enzymatic activity in human choriodecidua.

The aim of this study was to establish the effect of bacterial endotoxin lipopolysaccharide (LPS) on type II phospholipase A2 (PLA2) content and in vitro net PLA2 enzymatic activity in human choriodecidua. More particularly, the objective was to ascertain whether an increase in type II PLA2 tissue content and PLA2 enzymatic activity is associated with the previously documented stimulatory effect of LPS on prostaglandin E2 (PGE2) release from choriodecidua. Choriodecidua explants were incubated in RPMI 1640 (control) or RPMI 1640 containing LPS (0.1 ng/ml to 10 micrograms/ml) for up to 24 h. Under the incubation conditions utilized, LPS (1 microgram/ml) stimulated the release of PGE2 3-fold (p < 0.001, n = 4 tissues), in a time-dependent manner (p < 0.005). Tissue immunoreactive (ir)-type II PLA2 content and PLA2 enzymatic activity were determined by monoclonal antibody sandwich ELISA and radiolabeled enzyme assay procedures, respectively. The tissue content of type II PLA2 immunoreactivity in choriodecidua obtained from women (n = 7) at term but not in labor averaged 155 +/- 24 ng/ml DNA. PLA2 enzymatic activity average 29.8 +/- 5.1 pmol phosphatidylethanolamine (PE)/mg DNA/h. LPS at a concentration of 1 microgram/ml increased immunoreactive type II PLA2 tissue content by 180% of the control value (p < 0.05, n = 7) within 1 h of exposure and remained significantly elevated for 18 h when compared to controls (174% of control, p < 0.01, n = 7).(ABSTRACT TRUNCATED AT 250 WORDS)

Chorion↗
PubMed1994

50Hz interference and noise in ECG recordings--a review.

In this review paper, a simplified model is used to explain the various ways by which 50Hz interference can disturb electrocardiogram recordings. From the model, noise expressions are also derived which explain sources of noise in recordings. Means of minimising the 50Hz interference and noise with emphasis placed on skin abrasion and right-leg drive circuits are discussed. An add-on circuit which can be used with existing amplifiers to improve their performance is shown. Previous interference analysis has concentrated on 2-input differential amplifiers, however in modern hospitals, a wide variety of amplifier configurations are used. An example is the Wilson Central Terminal which is used to obtain a zero potential in body surface mapping applications. In this review it is shown with an example for an ECG amplifier incorporating a Wilson Central Terminal, how it is easy to extend the interference model to other applications.

Amplifiers, Electronic↗
PubMed1993

Negative and positive regulators modulate the activity of a silkmoth chorion gene during choriogenesis.

We have used in vitro linker substitution mutagenesis and P-element-mediated transformation in Drosophila to define cis-regulatory elements of the bidirectional promoter of the Bombyx mori A/B.L12 chorion genes in an in vivo situation. Within an essential 112 bp part of this promoter, mutations in two non-contiguous approximately 35 base-pair regions (A1 and A2) result in significant reduction of expression at late choriogenesis. The reduction occurs in both promoter orientations, indicating the existence of bidirectionally active positive elements. Mutations in A1, but not in A2, also lead to premature activation at early choriogenesis, suggesting the existence of a negative element essential for the finely tuned expression profile during choriogenesis. Normally, this element apparently prevents early expression; it also acts bidirectionally. The highly specific effects of these mutations suggest that several trans-acting regulators of chorion gene transcription have been conserved between silkmoths and fruitflies.

Animals↗
PubMed1993

Application of the random amplified polymorphic DNA technique for the detection of polymorphism among wild and cultivated tetraploid wheats.

Development of a high-density genetic linkage map of cultivated wheats using conventional molecular markers has lagged behind the other major food crops such as rice and tomato because of the large genome size and limited levels of genetic polymorphisms. Recently, random amplified polymorphic DNAs (RAPDs) have been suggested to provide an alternative to visualize more polymorphism. For the construction of a genetic linkage map in tetraploid wheats, one can use a strategy of intersubspecific crosses between the most dissimilar wild and cultivated tetraploid wheats that are easy to hybridize and result in fertile progeny. An assessment of the level of RAPDs among different accessions and varieties of wild and cultivated tetraploid wheats is required to fulfill this objective. We present here the data obtained using RAPD analysis of 40 primers in 20 accessions of wild tetraploid emmer wheats (Triticum turgidum L. ssp. dicoccoides) and 10 genotypes of cultivated tetraploid durum wheats (Triticum turgidum L. ssp. durum) selected from geographically diverse locations. We have observed a higher level of polymorphism among different accessions of wild emmer wheat from Israel. Turkey, and Jordan than the group of cultivated American, Turkish, and Syrian durum wheats. These data have been used to generate a dendrogram suggesting the genetic relationships among these genotypes, and the most dissimilar genotypes are identified for future mapping and gene tagging work.

Base Sequence↗
PubMed1993

A novel approach to the design of a Wilson referenced ECG amplifier.

The Wilson Central Terminal consists of three limb electrodes connected through a resistor network at the inverting input to the ECG amplifier. It is often used as a zero potential reference in ECG recordings. In this paper, the implications of using a Wilson central reference on the overall amplifier's common-mode rejection ratio and noise specifications is analysed. It is shown that the Wilson reference can degrade the overall amplifier specifications. The design of a Wilson referenced amplifier is then described which shows this to be true. A novel approach to the design of a Wilson referenced ECG amplifier is then presented, whereby the reference network is moved from the input to an intermediate stage of the amplifier. An analysis on the improvements achieved over the conventional approach is given. An amplifier design using the new approach is then described. Tests results showed a significant improvement in amplifier common mode rejection ratio and noise specifications when compared to the conventional design.

Electrocardiography↗
PubMed1992

In vitro activity of Ro 23-9424, a dual-action antibacterial agent, against bacterial isolates from cancer patients compared with those of other agents.

The in vitro activity of Ro 23-9424 against bacterial isolates from patients with cancer was compared with those of fleroxacin, ciprofloxacin, cefoperazone, and ceftazidime. Ro 23-9424 inhibited the majority of the members of the family Enterobacteriaceae and all Aeromonas isolates at a concentration of less than or equal to 1.0 micrograms/ml. It was also active against Acinetobacter spp. and Haemophilus influenzae, including beta-lactamase-producing strains. The MIC for 90% of isolates (MIC90) of Pseudomonas aeruginosa was 16.0 micrograms/ml. All group A and B streptococci were inhibited by less than or equal to 0.25 micrograms/ml, and 90% of group G streptococci and Streptococcus pneumoniae were inhibited by 1.0 micrograms/ml. All methicillin-susceptible strains of Staphylococcus aureus and 60% of methicillin-resistant strains were susceptible to 2.0 micrograms of Ro 23-9424 per ml, whereas the MIC90 for Staphylococcus epidermidis and Staphylococcus hominis isolates was 4.0 micrograms/ml. Staphylococcus haemolyticus and Enterococcus spp. were less susceptible; MIC90s for them were 16.0 and 32.0 micrograms/ml. Ro 23-9424 has a broad antibacterial spectrum and potential utility for therapy of infections in cancer patients.

Anti-Infective Agents↗
PubMed1991

Spectrum of Aeromonas and Plesiomonas infections in patients with cancer and AIDS.

The spectrum of infection with Aeromonas and Plesiomonas included gastroenteritis, bacteremia, biliary tract infection, perirectal infection, and disseminated disease. Most patients (86%) with bacteremia were neutropenic (less than 500 PMN/mm3). Colonization of stools and sputum also occurred. Therapy with aminoglycosides, beta-lactams, trimethoprim/sulfamethoxazole, and the newer quinolones was effective in patients with AIDS and cancer.

Acquired Immunodeficiency Syndrome↗
PubMed1991

Mammography in younger women.

Breast imaging is not frequently performed in women aged 35 years or younger for several reasons. Approximately half of the radiographic examinations of a breast symptom give normal results because the expected density of the breast in younger women may obscure abnormalities. Results from biopsies performed subsequent to positive mammogram findings confirm the predominance of benign lesions; cancers are rarely observed. After reviewing the main breast diseases that occur in the 20- to 35-year-old age group, we evaluated the accuracy of mammography in diagnosing malignancy, and attempted to summarize guidelines for breast imaging in young women, whose breasts are quite sensitive to radiation.

Adult↗
PubMed1991

Antifungal agents vs. boric acid for treating chronic mycotic vulvovaginitis.

Ninety-two women with chronic mycotic vaginal infections were followed with microscopic examination of the vaginal discharge during prolonged therapy with antifungal agents and boric acid. A microscopic picture unique to chronic mycotic vaginitis was observed, representing the cytologic reaction of the mucous membrane to chronic yeast infection. This diagnostic tool proved extremely effective in detecting both symptomatic and residual, subclinical mycotic infection and provided a highly predictive measure of the probability of relapse. The ineffectiveness of conventional antifungal agents appeared to be the main reason for chronic mycotic infections. In contrast, boric acid was effective in curing 98% of the patients who had previously failed to respond to the most commonly used antifungal agents and was clearly indicated as the treatment of choice for prophylaxis.

Administration, Intravaginal↗
PubMed1990

Drying acrylamide slab gels for fluorography without using gel drier and vacuum pump.

A method for drying acrylamide slab gels for fluorography without using a gel drier and a vacuum pump is described. The method involves the use of inexpensive acrylic frames, cellophane, and plastic supplies. The fluorographs obtained from gels dried by this method are comparable to those obtained using a gel drier and a vacuum pump. Several gels can be dried by this method simultaneously at room temperature. The method is less time consuming and is economical and practically crack free.

Acrylamide↗